Monthly RACMO2.4p1 data for Antarctica (11 km) for SMB, SEB and near-surface variables (1979-2025)

Version 2: Extended to December 2025.

This data set includes the surface mass balance (SMB) components, surface energy budget (SEB) variables and near-surface climate variables as is simulated by the regional atmospheric climate model RACMO2.4p1 over Antarctica from January 1979 to December 2025. At the lateral boundaries, RACMO is forced with ERA5 multilevel data of wind speed, temperature, humidity and pressure. At the sea-surface boundary, sea ice extent and sea surface temperature are also forced by ERA5. RACMO is run with 40 vertical levels and on an 11 km horizontal resolution grid. The domain includes Antarctica, the Drake passage and parts of Patagonia.

Variables are monthly-averaged (named monthlyA), monthly-accumulated (named monthlyS), or part of the mask file. Variables ending with ‘gl’ are for glaciated surfaces only. Integrating a variable over the doman (e.g., calculating the SMB in Gigaton per month) requires multiplying the variable with the grid cell area (‘Area’) and ice mask (‘IceMask’) fields, both can be found in the ANT11_masks.nc file. The ice mask is a fractional field since RACMO2.4p1. If limiting the integration to the ice sheet only, the considered variable has to be multiplied with the ‘Icesheet_Only’ field that is also available in the mask file, in addition to multiplying it with the grid cell area and ice mask. The mask file includes more fields, which are also listed below. Unlisted variables and listed variables with a higher temporal resolution are available on request. This data set includes the following variables: 

Surface mass balance (SMB) variables (in kg m^-2 mo^-1 or mm water equivalent mo^-1):

smbgl: (Specific) Surface mass balance

mltgl: Surface snow melt production

rfrzgl: Refreezing of liquid water

sf: Solid precipitation

pr: Total precipitation (to determine rain: ra = pr – sf)

prgl: Total precipitation for glaciated surfaces only

totrunoff: (Near-)surface meltwater runoff on glaciated surfaces

subltot: Sublimation of snow (including sublimation of suspended snow in the atmosphere caused by blowing snow). Negative values are sublimation, positive values are riming.

sndivgl: Erosion of blowing snow

Surface Energy Budget (SEB) variables (in J m^-2): 

To convert to W m^-2, divide by the number of seconds in a month.

rsds: Downwelling shortwave radiation at the surface

rsusgl: Upwelling shortwave radiation at the surface

rlds: Downwelling longwave radiation at the surface

rlusgl: Upwelling longwave radiation at the surface

hfssgl: Sensible heat flux, defined positive towards the surface

hflsgl: Latent heat flux, defined positive toward the surface

gbot: Ground heat flux for glaciated surfaces

Other variables:

tas: Near-surface air temperature (2 m above the surface)

ts: Surface temperature (skin temperature)

huss: Near-surface specific humidity (2 m above the surface

hurs: Near-surface relative humidity (2 m above the surface)

ps: Surface pressure

sfcwind: Near-surface wind speed

u10m: Zonal wind speed at 10 m above the surface

v10m: Meridional wind speed at 10 m above the surface

Fields available in the mask file:

lat: Latitude

lon: Longitude

lat_bnds: Latitude of the four corners of each grid point

lon_bnds: Longitude of the four corners of each grid point

IceMask: Ice mask fraction (grounded ice and ice shelves)

LSM: Land-sea mask (0 or 1)

Geopotential: Geopotential height

Topography: Topographic height of the surface

Area: Surface area of each grid point

Basins: Drainage basins following the IMBIE convention

Icesheet_Only: Mask showing which grid points are considered to be part of the Antarctic ice sheet (0 or 1)